assistance, the task is not trivial, and antenna system design often comes down to repeatedly testing a design’s performance and then refining the layout.
ground plane and clearance area redesign, and/or matching circuit tuning.
boards for both the NN02-220 and NN03-310 antennas, the EB_NN02- 220-1B-2R-1P and EB_NN03-310- M+5G, respectively. In each case, the evaluation boards include the antenna, impedance matching circuits, and the grounded 50 Ω micro-coaxial cable (Figure 6). A designer can plug the evaluation boards into a network analyser to familiarise themselves with the frequency response they might expect from a similar prototype design, before moving on to product testing. The final examination of the cellular IoT device’s performance should be made in an anechoic chamber. This is the ultimate test of a design which often reveals weaknesses in efficiency and omnidirectional performance that don’t show up during network analyser testing. Deficiencies might require a revised embedded antenna selection,
Conclusion
The small size and multi-frequency operation of many IoT products makes antenna implementation a challenge. Separate antennas and matching circuits for each frequency can be tough to accommodate, and they add complexity and cost. Embedded antennas offer an option to save space by using a single device to serve multiple frequencies. The trade-off is that ground plane, clearance, and matching circuit design becomes even more difficult. However, embedded antenna suppliers offer proven design advice and software modelling tools that can ease the design cycle. Even with this
Figure 6: The Ignion antenna evaluation boards include a grounded 50 Ω micro- coaxial cable which can be connected
to a network analyser. Image source: Ignion
Figure 5: Simulated VSWR and efficiency results for the reference design shown in Figure 3, using the NN03-310 and matching circuit’s component values calculated by the Ignion design software. Image source: Ignion
we get technical
37
Powered by FlippingBook